Electric circuit breaker



Feb. 16, 1'937. c. THuMlM ELECTRIC CIRCUIT BREAKER Filed June 6, 1935 my. w..- m mm w T VMA n IQ .l @w W U D Feb. 16, 1937. c. THUMIM ELECTRICCIRCUIT BREAKER Filed June 6, 1935 OIL LEVEL Inventor: Cond Thu x Z Y 39 a 4 J 3 3 5 ,H J v, Z ,H 7 3 .l a H, p .h 4, n ll Q V, l* :IJ 4 .f f WM 5 m la 5 Z ,d im 4 H 5 u n Y 8 m.. a l 4 G 7 W.

Patented Feb. 16, 1931 PATENT OFFICE ELEUI'RIC CIBCIIIT BBEAKER CarlThumim, Yeadon, Pa., assignor to General Electric Company, a corporationof New York Application June 6,

4 Claims.

My invention relates to electric circuit breakers, more particularly tooperating and controlling means for high tension multiple-break electriccircuit breakers of the liquid blast or impulse 5 type, and has for itsprincipal object the provision of an improved and simpliiied electriccircuit breaker of the aforesaid type.

My invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is an elevational view of the mainportion of an electric circuit breaker of the impulse type to which myinvention may be applied; Fig. 2 is an elevational view, partly insection, of a portion of the circuit breaker shown by Fig. l, and Fig. 3is a similar view wherein the mechanism shown by Fig. 2 is in anotherposition.

Fig. 1 illustrates a high tension multiple-break electric circuitbreaker of the impulse type comprising a pair of similar interruptingunits I and 2 for interrupting a high tension power circuit indicated at3. Each interrupting unit is pivotally mounted at 4 on a stationaryinsulating support 5, the free terminalends of the interrupting unitseach having a non-rigid connection with an insulating support 8.

'I'he operating means for the interrupting units includes an operatingrod 'I which extends upwards from suitable operating mechanism (notshown) through the hollow insulating support 5 and terminates in linkagecoacting with the interrupting units. The insulating supports 5 and 8together with the operating mechanism above referred to are suitablymounted on structural steel framework or other rigid foundation.

Referring more particularly to Fig. 2, the interrupting unit 2, which isgenerally similar in all respects to the interrupting unit I, comprisesa metallic housing or casing 8 to which is united an elongatedinsulating casing 8 comprising a cylindrical tube of mechanically stronginsulating material. The tube 9 is secured at III to an annular an'ge ofthe casing 8 and is in communication with the interior of said casing.The opposite-end of the tube is closed to form with the casing 8 areservoir for suitable arc-extinguishing liquid, such asoil for example.

For the purpose of insulating and for protecting the interrupting unitfrom the effects of weather and climate, an outer insulating casing isprovided comprising a pair of insulating shells 193s, serial No. 25,222

(ci. o-15o) II and I2 of ceramic material suitably united at adjacentends by a fluid-tight ilexible connection, such as a metallic bellows I3for example. The insulating shell II is suitably connected at one end atI4 to an annular flange I5 of the casing 8, the other shell I2 beingclosed at its outer end by terminal structure 3.

The annular space I8 between the tube 8 and shells Il and I2 is sealedwith respect to the interior of the tube 9 and is lled with insulatingoil. The oil space I6 is in communication with an oil reservoir andexpansion chamber i8' formed by the casing 8. Accordingly, accidentalbreakage of one of the insulating shells would permit escape only of theoil in the space I6, thereby permitting continued normal operation ofthe interrupting unit.

The mounting for the interrupting unit comprises a pivotal support 4 towhich the casing 8 is directly connected, and the unit at its other endis provided with a non-rigid sliding connection with the support 6. Thisarrangement permits a limited amount of relative movement between theinterrupting uni and the stationary support 5 insulating the operatingunit.

The operating rod I extending through the central insulating support 5is connected through a link Il to an operating lever I8 which ispivotally mounted at I 9 within the casing 8 and extends through a wallof the casing 8, as illustrated, to the link connection at 2li. Theoperating rod l operates within a tubular casing 2| which is providedwith a T-connection at 22 for enclosing the connection between theoperating rod and the operating levers I8 of both interrupting units.The T-connection includes a sleeve member 23 extending through a wall ofthe casing 8 and having a sliding liquid-tight seal therewith at 24.Accordingly, a limited movement of the interrupting unit about thepivotal support 4 is permitted without loss of oil from the interruptingunit during operation thereof.

The circuit interrupting means comprises a plurality of pairs ofcontacts 25-26, 2I-28, etc. connected in series and arranged generallyalong the longitudinal axis of the insulating tube 9. The contacts aremounted on and supported by an insulating partition 29 extendinglongitudinal- Y and force the partition 29 into ilrm engagement with thetube 9.

The relatively movable contact structure at each break comprises a pairof butt contacts 25 and 25, each movable contact being connected bymeans of a crosspece or yoke 32 to a pair oi spaced rods 33. The rodsare guided and supported by rollers 3F; carried by depending insulatingmembers 36 for reciprocal longitudinal movement with respect to thecoasting stationary contacts. The movable and stationary contacts oi?adjacent pairs of contacts are electrically connected by Flexibleconductors 35, thereby connecting the respective pairs of contacts inseries. Each stationary contact is rigidly mounted on an insulatingmember 35 depending from the partition lice .partition 29 is providedwith an exhaust opening 3l adjacent the point of separation of each pairof contacts. The arrangement is such that arc-extinguishing liquidfilling the lower chamber and. placed under pressure during the openingoperation forces a jet of oil across the arc path, through the exhaustpassage into the chamber above the partition.

The source of pressure `for driving the oil from the lower chamberthrough the arcs into the upper chamber in accordance with a circuitopening operation comprises in the present instance a piston which isoperatively associated with the contact operating means so that a highvelocity jet of oil is directed across the arc gap immediately uponseparation of the contacts and after said contacts are separated.

Referring more particularly to Fig. 2, the sourcev of pressure comprisesa piston 38 operable in an open end cylinder 39 formed in the casing 8.Y

The piston 38 is operatively connected through a link 40 to theoperating lever I8 and is provided with valves 4| disposed in theoperating face of the piston so as to be rmly seated and closed by fluidpressure during the downward or working stroke of the piston, and toopen on the return stroke of the piston for passing oil above the pistoninto the lower reservoir 8 in the casing 8. The space above thepartition 29 is in free communicaton with the space in thecasing abovethe piston and defined by the separating wall structuren so thatoil inthe upper chamber after each interruption may circulate back through thepiston to the reservoir 8'.

A flap valve 43, pivoted at 44, is arranged to close the passage betweenthe piston and the main lower chamber during the return or suctionstroke of the piston. The'valve 43 opens freely under iiuld pressure onthe working stroke of the 'piston'. By this arrangement, oil, instead ofbeing sucked back into the lower chamber after an arc-interruptingoperation, is drawn into the casing 8 where it directed through thepiston to the reservoir 8'. Since the quantity of oil for a singleinterrupting operation is comparatively small, the valves 4l and 43insure substantially complete circulation of the oil for successivecircuit interrupting operations before re-use. Consequently, the rate ofoil deterioration due to carsubjected to a transverse oil jet.

Koil across the arc path continues at high velocity accrues contactstructure which might result were air or gas sucked from the upperchamber through the exhaust port into the lower chamber. Furthermore,the presence of air or gas beneath the partition 29 would tend to deferthe buildingup ol' pressure in the otherwise substantiallyincompressible arc-extinguishing liquid and so delay the blast eect.

The Contact opening and closing mechanism associated with the lever i8comprises a bellcranlr lili, one arm it of which is provided with aroller lll for coacting with oppositely disposed cam members il@ and lilcarried by the member i3. Another arm bil of the bellcrank is connectedby meansoi a yoke, or' the like, at 5l to the pair of contact supportingrods 33, the arrangement being such that rotation of the bellcranir inopposite directions causes opening or closing movement of the contacts.Another arm oi the ci" d5 is connected to a compression spring 52 havinga pivotal support at 53 with respect to the casing t. The guide pin Elliof the compression spring 52 is pivotally connected to the cranlif at55. As illustrated in Fig. 2, the contacts are closed and the spring 52is slightly over-center with respect to the crank pivot and pivot bil.Accordingly, the crank 45 is biased by the spring in clockwisedirection, thereby holding the contacts by means of the rods 33 inclosed position.

For the purpose of correlating the contact ope -ng movement and thefluid pressure created by Vhe piston 38, the operating lever i3- isprovided with a lost motion connection with the contacts comprising thepair of spaced cam plates 48 and 49 having cam surfaces 48 and 49arranged to coact with the crank roller 4l. The cam face 49' coacts withthe roller 4T in the circuit opening operation and the cam face 48 inthe closing operation. When the operating rod 1 is lowered, as viewed inFig. 2, for effecting the contact'opening operation, the consequentcounter-clockwise movement of the lever I8 effects not only the workingstroke of ,the piston 38 for placing the oil in the lower chamberunderpressure but also counter-clockwise rotation of crank 45 by reasonof the camming action between the face 49 and roller 41 for opening thecontacts. The cam face 49' is designed so that a comparatively quickcontact separation is obtained at the initiation of the circuit' openingmovement, after which the rate of separation is decreased or isindependent of the cam operator coincident with the oil blast across thearcs. The compression spring 52 furthermore, after it has passed itsover-center position, biases the contacts towards the completely openposition as clearly illustrated by Fig. 3. This spring may if desiredconstitute the sole opening means after initial separation of thecontacts by reason of suitable spacing between the cams 48 and 49. Forthe purpose of minimizing shock during the circuit opening operation, asuitable dashpot device indicated at 56 is positioned in the path of thelower arm of the crank 45 so as to take up the force ofthe spring 52. n

It will be noted that in thecircuit opening l l operation the oil in thelower chamber is placed under pressure by the piston .immediately aftermovement of the operating rod 1. In fact, the

ow of oil into the upper chamber through the port 31 is under way at theinstant of contact separation so .that the short arc path is at once Theflow of when the contacts have separated a predetermined distance, thecircuit generally being interrupted within several half cycles ofarcing. The continued separation of the contacts under the iniluenceofthe spring 52, and if desired the cam face 49 is accompanied bycontinued oil ilow through the ports 31 so as to clear all gases andproducts of arcing from the vicinity of the contacts.'

The circuit closing operation is effected by raising the operating rod 1and lever I8 so as to force, by means of the cam face 43', the crank 4 5in clockwise direction to the position shown in Fig. 2. The contact rods33 are moved towards the left and the contacts closed. During thecircuit closing operation the spring 52 is again compressed and moved toits overset contact restraining position.

Accordingly, my invention is particularly adapted to circuit breakers ofthe liquid blast type wherein a quick initial separation of the contactscoincident with the arc interrupting blast is desirable. Moreparticularly, the contact operating mechanism is considerably simplifiedby utilizing an auxiliary force, such as a double function spring, forcompleting the opening after the initial separation and for holding thecontacts in engagement. This eliminates the necessity for comparativelycomplicated variable speed controlling means.

The mounting for the interrupting units I and 2 and certain otherfeatures, such as the contact unit and valve structures, form no part ofthe present invention and are described and claimed in a copendingapplication entitled Electric circuit breakers", Serial No. 25,267,illed concurrently herewith by David C. Prince and assigned to the sameassignee as the present invention.

It should be understood that my invention is not limited to speciilcdetails of construction and arrangement thereof herein illustrated, andthat changes and modii'lcations may occur to one skilled in the artwithout departing from the spirit of my invention.

What I claim as new and desire to secure by letters Patent of the UnitedStates, is,-

l. An electric circuit breaker of the liquid blast type comprisingrelatively movable contacts, operating means having a lost motionconnection with said contacts for effecting to a predetermined extentpositive initial separation of said contacts, resilient means forindependently biasing said contacts at a lower rate toward open circuitposition after said initial separation, and pressure producing meansoperatively connected to said operating means for causing anarc-extinguishing blast of liquid across said contacts at a continuouslyhigh rate during both the initial and nal separation thereof.

2. An electric circuit breaker comprising relatively movable contacts,operating means for ei'- fecting separation of said contacts including acam arranged to cause initial separation of said contacts at acomparatively high rate and a spring arranged to bias said contactstoward completely open lcircuit position after .said initial separation,and means operatively connected to said cam for causing anarc-extinguishing blast of liquid across said contacts at a continuouslyhigh rate during both the initial and final separation thereof.

3. An electric circuit breaker comprising relatively movable contacts,operating means for said contacts comprising a crank operativelyconnected to said contacts, a lever having oppositely disposed cammembers for coacting with a portion of said crank and an over-centerspring connected to said. crank, circuit opening movement of said levereiecting through one oi' said cam members initial separation of saidcontacts. said over-center spring thereupon biasing said contactstowards completely open circuit position, and a piston operativelyconnected to said lever for directing an arc-extinguishing liquid acrosssaid contacts upon separation thereof, the other of said cam memberscausing during opposite movement of said lever closing movement of saidcontacts and compression of said spring ,to an over-center position forbiasing said conmovement of said contacts, means including said v leverfor placing said spring under compression 'v in the closed contactposition thereby biasing said contacts into engagement, and a pistonconnected to said operatingmeans and independent of said spring forcausing during both the initial and ilnal separation anarc-extinguishing 5 blast of liquid across said contacts in accordancewith the circuit opening movement.

CARL THUMIM.

